On Nov 30, 2007, at 12:13 AM, John Campbell wrote:
include_once is a real performance drag. You should use better
program
logic to make it possible to use a regular include call.
That is news to me. Why is include_once a performance drag?
This is a pretty controversial topic.
The theory about include_once being a performance drag is because it
has to do file system checks to get the real path of the file to make
sure it hasn't already included it. There were major issues with this
in early versions of PHP5, but has since been resolved.
What is the better programming logic, that doesn't just duplicate
the behavior?
I find it difficult to not use include_once/require_once in a large
application. You can use __autoload or something like this:
if (!class_exists('SomeClass') {
require 'SomeClass.php';
}
or
if (!function_exists('SomeFunction') {
require 'SomeLibrary.php';
}
That requires some good naming conventions and file system mapping to
create efficiently. Otherwise you end up with some crazy switch
statement.
In addition to that, it puts conditional logic around the includes.
From what I understand, opcode caches like APC scan the code for
includes to cache, but won't use the cache very well if the include is
inside any kind of conditional logic. Therefore, I've stuck with my
include_once/require_once statements which are almost all outside of
any conditional logic.
But this whole thing has been hazy to me and I have a feeling the php
internal developers might have conflicting feelings on it.
I just did a little web searching and found this guys blog. Pretty
cool stuff... he obviously knows what's going on here. I recommend
reading all the posts from bottom to top. Almost half of them apply
to this include problem. He wrote a tool that analyzes your code to
determine how the Zend engine and APC are handling your includes.
It's called Inclued:
http://t3.dotgnu.info/blog/php/
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